(19)

(11)

EP 4 018 246 A1

(12)

(43) Date of publication: 29.06.2022 Bulletin 2022/26 (21) Application number: 20761877.8 (22) Date of filing: 20.08.2020

(51) International Patent Classification (IPC):  G02B 27/00(2006.01) G02B 27/01(2006.01) (52) Cooperative Patent Classification (CPC): G02B 27/0081; G02B 27/0101; G02B 2027/0125 (86) International application number: PCT/GB2020/051994 (87) International publication number: WO 2021/032982 (25.02.2021 Gazette 2021/08)

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR Designated Extension States: BA ME Designated Validation States: KH MA MD TN (30) Priority: 21.08.2019 GB 201911982 28.11.2019 EP 19275135 (71) Applicant: BAE SYSTEMS plc London SW1Y 5AD (GB)	(72) Inventor: MASON, Stephen Rochester Kent ME1 2XX (GB) (74) Representative: BAE SYSTEMS plc Group IP Department  Warwick House P.O. Box 87 Farnborough Aerospace Centre Farnborough Hampshire GU14 6YU Farnborough Hampshire GU14 6YU (GB)